FoxESS US Series User manual

US SERIES
User Manual
FOXESS CO., LTD.

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Table of Contents
1. Notes on This Manual ............................................................................................................................ 3
1.1 Scope of Validity .......................................................................................................................... 3
1.2 Target Group ................................................................................................................................3
1.3 Symbols Used ..............................................................................................................................3
2. Safety Precautions ................................................................................................................................. 5
2.1 Appropriate Usage .......................................................................................................................5
2.2 PE Connection and Leakage Current .......................................................................................... 5
3. Introduction ............................................................................................................................................ 7
3.1 Basic Features .............................................................................................................................7
3.2 Dimensions .................................................................................................................................. 8
3.3 Terminals of Hybrid Inverter .........................................................................................................9
4. Technical Data ......................................................................................................................................10
4.1 PV Input (For Hybrid Only) ........................................................................................................ 10
4.2 Battery ....................................................................................................................................... 10
4.3 AC Output/Input ......................................................................................................................... 11
4.4 Efficiency, Protection and Standard ...........................................................................................13
4.5 General Data ............................................................................................................................. 14
5. Installation ............................................................................................................................................16
5.1 Check for Physical Damage ...................................................................................................... 16
5.2 Packing List ............................................................................................................................... 16
5.3 Mounting ....................................................................................................................................16
6. Electrical Connection ........................................................................................................................... 23
6.1 Battery Connection .................................................................................................................... 23
6.2 PV Connection (For Hybrid Only) .............................................................................................. 24
6.3 Grid Connection .........................................................................................................................25
6.4 Communication Device Installation (Optional) ...........................................................................27
6.5 E-STOP Wiring .......................................................................................................................... 28
6.6 FOX Hub Wiring .........................................................................................................................29
6.7 System Wiring Diagram ............................................................................................................. 31
6.8 Hybrid Inverter Start-Up .............................................................................................................33
6.9 Hybrid Inverter Switch Off ..........................................................................................................33
7. Operations on the FoxEssUS App ....................................................................................................... 34
7.1 App Overview .............................................................................................................................34
7.2 Downloading and Installing the App .......................................................................................... 34
7.3 Registering the App ................................................................................................................... 34
7.4 Resetting the Password .............................................................................................................36
7.5 WIFI Configuration .....................................................................................................................36
7.6 App Operations by the Installer ..................................................................................................38
7.7 App Operations by the End User ............................................................................................... 46
8. Operation ............................................................................................................................................. 55
8.1 Control Panel ............................................................................................................................. 55
9. Maintenance .........................................................................................................................................56
9.1 Alarm List ...................................................................................................................................56

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9.2 Troubleshooting and Routine Maintenance ............................................................................... 67
10. Decommissioning ...............................................................................................................................69
10.1 Dismantling the hybrid inverter ................................................................................................ 69
10.2 Packaging ................................................................................................................................ 69
10.3 Storage and Transportation ..................................................................................................... 69

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1. Notes on This Manual
1.1 Scope of Validity
This manual describes the assembly, installation, commissioning, maintenance and troubleshooting of
the following model(s) of FOXESS products:
H1-3.8-US H1-5.7-US H1-7.6-US H1-9.6-US H1-11.4-US
AC1-3.8-US AC1-5.7-US AC1-7.6-US AC1-9.6-US AC1-11.4-US
Note: Please keep this manual where it will be accessible at all times.
1.2 Target Group
This manual is for qualified electricians. The tasks described in this manual only can be performed by
qualified electricians.
1.3 Symbols Used
The following types of safety instructions and general information appear in this document as described
below:
Danger!
“Danger” indicates a hazardous situation which, if not avoided, will result in death or
serious injury.
Warning!
“Warning” indicates a hazardous situation which, if not avoided, could result in
death or serious injury.
Caution!
“Caution” indicates a hazardous situation which, if not avoided, could result in minor
or moderate injury.
Note!
“Note” provides important tips and guidance.
Table 1-1 Label Description
This section explains the symbols shown on the inverter and on the type label:
Symbols
Explanation
Certified to meet the requirements of CSA-C22.2 No. 107.1-16, UL Std.
No. 1741-Third Edition, UL 1741 SB, IEEE 1547-2018, IEEE
1547.1-2020, and CA Rule 21.
Beware of burning.
The case temperature may exceed 140°F (60℃) during operation. Avoid
contact during operation.
Danger of high voltages.
Disconnect from the grid and the PV generator before opening the device.

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Table 1-2 Label Description
Danger.
Risk of electric shock!
Danger to life due to high voltage.
There is residual voltage in the inverter which needs 5 min to discharge.
Wait 5 min before you open the upper cover or the lower cover.
Read the manual.
Product should not be disposed as household waste.

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2. Safety Precautions
2.1 Appropriate Usage
US series hybrid inverters are designed and tested in accordance with international safety requirements.
However, certain safety precautions must be taken when installing and operating this hybrid inverter. The
installer must read and follow all instructions, cautions and warnings in this installation manual.
-All operations including transport, installation, start-up and maintenance, must be carried out by
qualified, trained personnel.
-The electrical installation & maintenance of the hybrid inverter shall be conducted by a licensed
electrician and shall comply with local wiring rules and regulations.
-Before installation, check the unit to ensure it is free of any transport or handling damage, which
could affect insulation integrity or safety clearances. Choose the installation location carefully
and adhere to specified cooling requirements. Unauthorized removal of necessary protections,
improper use, incorrect installation and operation may lead to serious safety and shock hazards
or equipment damage.
-Before connecting the inverter to the power distribution grid, contact the local power distribution
grid company to get appropriate approvals. This connection must be made only by qualified
technical personnel.
-Do not install the equipment in adverse environmental conditions such as in close proximity to
flammable or explosive substances; in a corrosive or desert environment; where there is
exposure to extreme high or low temperatures; or where humidity is high.
-Do not use the equipment when the safety devices do not work or are disabled.
-Use personal protective equipment, including gloves and eye protection during the installation.
-Inform the manufacturer about non-standard installation conditions.
-Do not use the equipment if any operating anomalies are found. Avoid temporary repairs.
-All repairs should be carried out using only approved spare parts, which must be installed in
accordance with their intended use and by a licensed contractor or authorized FOXESS service
representative.
-Liabilities arising from commercial components are delegated to their respective manufacturers.
-Any time the hybrid inverter has been disconnected from the public network, please be
extremely cautious as some components can retain charge sufficient to create a shock hazard.
Prior to touching any part of the hybrid inverter please ensure surfaces and equipment are
under touch safe temperatures and voltage potentials before proceeding.
2.2 PE Connection and Leakage Current
PV System Residual Current Factors
-In every PV installation, several elements contribute to the current leakage to protective earth
(PE). These elements can be divided into two main types.
-Capacitive discharge current-Discharge current is generated mainly by the parasitic
capacitance of the PV modules to PE. The module type, the environmental conditions (rain,
humidity) and even the distance of the modules from the roof can effect the discharge current.
Other factors that may contribute to the parasitic capacitance are the inverter’s internal
capacitance to PE and external protection elements such as lighting protection.
-During operation, the DC bus is connected to the alternating current grid via the inverter. Thus, a
portion of the alternating voltage amplitude arrives at the DC bus. The fluctuating voltage

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constantly changes the charge state of the parasitic PV capacitor (i.e. capacitance to PE). This
is associated with a displacement current, which is proportional to the capacitance and the
applied voltage amplitude.
-Residual current-if there is a fault, such as defective insulation, where an energized cable
comes into contact with a grounded person, an additional current flows, known as a residual
current.
Residual Current Device (RCD)
-All FOXESS hybrid inverters incorporate a certified internal RCD (Residual Current Device) to
protect against possible electrocution in case of a malfunction of the PV array, cables or inverter
(DC). The RCD in the FOXESS inverter can detect leakage on the DC side. There are 2 trip
thresholds for the RCD as required by the UL1741 standard. A low threshold is used to protect
against rapid changes in leakage typical of direct contact by people. A higher threshold is used
for slowly rising leakage currents, to limit the current in grounding conductors for the safety. The
default value for higher speed personal protection is 30mA, and 30mA, 60mA, 150mA per unit
for lower speed fire safety.

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3. Introduction
3.1 Basic Features
US series is high-quality hybrid inverters which can convert solar energy to AC energy and store energy
into battery. The hybrid inverter can be used to optimize self-consumption, store in the battery for future
use or feed-in to public grid. Work mode depends on PV energy and user’s preference.
• System advantages:
-Easy installation: flexible configuration, plug and play set-up
-High Voltage：compatible with high-voltage batteries for maximum round-trip efficiency.
-Type 4X: engineered to last with maximum flexibility, and suitable for outdoor installation.
-Remote monitoring：monitor your system remotely via smartphone app or web portal.
-100% imbalance for Split-Phase Loads.
-High backup power, up to 12.5kW.
-High scalability, up to 4 inverters in parallel.
-Fast battery charging, up to 50A changing and 60A discharging current.
-RSD transmitter inside: a Tigo or APsystem transmitter is integrated in the inverter ，and
only RSD receivers should be installed by the installer.
-RGM inside：a 0.5% accuracy revenue grade meter (RGM) is integrated in the inverter and FOX
Hub to finance the solar array.
-UPS switchover time: the switchover time from on-grid to off-grid or from off-grid to on-grid is
less than 15ms.
-Generator ready: the FOX Hub is ready to connect to an up to 200A generator.
-Smart loads: 240V or 120V loads can be connected to the FOX Hub and controlled according
to the time and SOC.
-Safety&Reliability: transformerless design with software and hardware protection.
-Arc detection function: capability of detecting up to 35A arc current. When the PV panel
produces arc, the inverter will shut down immediately, disconnect the grid side relay, BDC relay
will send shutdown instructions to the battery to disconnect the battery. Meanwhile, turn off the
quick shut-off device (RSD) to avoid the fire of the PV panel. After the arcing occurs, the inverter
will report the arcing fault immediately and upload it to the cloud.
• Work modes:
Work modes
Description
Self-use
(with PV Power)
Priority: load>battery>grid
The energy produced by the PV system is used to optimize self-consumption.
The excess energy is used to charge the batteries, and then exported to gird.
Self-use
(without PV Power)
When no PV supplied, battery will discharge for local loads firstly, and grid will
supply power when the battery capacity is not enough.
Time-of-use
Priority: battery>load>grid (when charging)
Priority: load>battery>grid (when discharging)
This mode applies the area that has electricity price between peak and valley.
User can use off-peak electricity to charge the battery.
The charging and discharging time can be set flexibly, and it also allows to
choose whether charge from the grid or not.

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Back up mode
When the grid is off, system will supply emergency power from PV or battery to
the home loads (Battery is necessary in off-grid mode).
Load shifting mode
This is the preferred mode under a time-of-use rate schedule in which mode the
user can set the On peak, Off peak, and Mid peak hours.
Load Shifting provides users with two options: solar power to storage first, and
solar power to family loads first.
Table 3-1 Work Mode Description
Note: Charging time is when the battery is charged within the set time range. The setting of time can be
used in the above three modes.
3.2 Dimensions
Figure 3-1 Enclosure Dimensions

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3.3 Terminals of Hybrid Inverter
Figure 3-2 Bottom of Hybrid Inverter
Item
Description
A
BAT
B
PV (For Hybrid Only)
C
WIFI/GPRS/4G/USB
D
AC-GRID
E
AC-BACKUP
F
DC Switch (For Hybrid Only)
G
Waterproof Lock Valve
H
Waterproof Lock Valve
I
COM1
J
COM2
Table 3-2 Terminal Description